Determining electrical submersible pump lifetime expectancy

Abstract

An assembly and a method for determining a lifetime expectancy of the electrical submersible pump. An assembly includes a motor, a motor head coupled to the motor, a power cable, a sensor module, and a local controller. The motor head has one or more toroidal transformers. The power cable extends into the motor head through the toroidal transformers to the motor. The sensor module receives power from toroidal transformers, detects a condition of the motor, and transmits a signal representing the condition of the motor. The local controller receives electrical power from the toroidal transformers; receives the signal representing the condition of the motor; based on the condition of the motor, determines a mass flow rate of the motor; and based on the mass flow rate of the motor, determines a life expectancy of the motor.

1 . An electrical submersible pump assembly comprising:
 a motor;   a motor head coupled to the motor, the motor head comprising one or more toroidal transformers;   a power cable extending into the motor head through the one or more toroidal transformers to the motor;   a sensor module configured to perform operations comprising:
 receiving power from the one or more toroidal transformers; 
 detecting a condition of the motor; and 
 transmitting a signal representing the condition of the motor; and 
   a local controller contained within the motor head, the local controller coupled to the motor and the sensor module, the local controller configured to perform operations comprising:
 receiving electrical power from the one or more toroidal transformers; 
 receiving the signal representing the condition of the motor; 
 based on the condition of the motor, determining a mass flow rate of the motor; and 
 based on the mass flow rate of the motor, determining a life expectancy of the motor. 
   
     
     
         2 . The electrical submersible pump assembly of  claim 1 , further comprising a temperature sensor configured to detect a differential temperature of a fluid passing across an outer surface of the motor and transmit a signal representing the differential temperature to the local controller. 
     
     
         3 . The electrical submersible pump assembly of  claim 2 , wherein the temperature sensor comprises:
 a downhole temperature sensor positioned at a downhole end of the motor, the downhole temperature sensor configured to sense a downhole end temperature of the fluid and transmit a signal representing the downhole end temperature to the local controller; and   an uphole end temperature sensor positioned at an uphole end of the motor, the uphole end temperature sensor configured to sense an uphole end temperature of the fluid and transmit a signal representing the uphole end temperature to the local controller.   
     
     
         4 . The electrical submersible pump assembly of  claim 1 , wherein the condition of the motor is the differential temperature across the outer surface of the motor, determining the mass flow rate of the motor comprises calculating the mass flow rate by 
       
         
           
             
               
                 
                   m 
                   ˙ 
                 
                 = 
                 
                   
                     Q 
                     ˙ 
                   
                   
                     
                       C 
                       p 
                     
                     ( 
                     
                       
                         T 
                         out 
                       
                       - 
                       
                         T 
                         in 
                       
                     
                     ) 
                   
                 
               
               , 
             
           
         
       
       wherein {dot over (m)} is the mass flow rate of fluids in the motor in kg/sec, {dot over (Q)} is the energy supplied in the motor in Watts, C p  is a specific heat capacity of the fluid in J/kgK in the motor, T out  is a fluid temperature at the motor uphole end in ° C., and T in  is a fluid temperature at the motor downhole end in ° C. 
     
     
         5 . The electrical submersible pump assembly of  claim 4 , wherein determining the life expectancy of the motor based on the energy loss of the motor comprises comparing the actual energy loss and the calculated mass flow rate to a design energy loss and a design mass flow rate for the motor on an efficiency curve plot. 
     
     
         6 . The electrical submersible pump assembly of  claim 5 , wherein the local controller is further configured to transmit the determined life expectancy of the motor to a remote controller. 
     
     
         7 . The electrical submersible pump assembly of  claim 1 , wherein:
 the power cable comprises three conductors, each of the three conductors configured conduct a different phase of a three-phase electrical signal to the motor; and   the one or more toroidal transformers comprises three toroidal transformers, each of the three conductors positioned through a different toroidal transformer.   
     
     
         8 . The electrical submersible pump assembly of  claim 1 , wherein:
 the power cable comprises a single conductor; and   the one or more toroidal transformers comprise one toroidal transformer.   
     
     
         9 . The electrical submersible pump assembly of  claim 1 , wherein the motor head further comprises an electrical storage device electrically coupled to the one or more toroidal transformers, the sensor module, and the local controller. 
     
     
         10 . The electrical submersible pump assembly of  claim 9 , wherein the electrical storage device comprises one or more of a battery or a capacitor. 
     
     
         11 . The electrical submersible pump assembly of  claim 1 , wherein the motor head further comprises a dielectric oil sensor configured to:
 sense a dielectric condition of the dielectric oil in the motor head received from the motor; and   transmit a signal representing a value of the dielectric condition of the dielectric oil in the motor head to the local controller.   
     
     
         12 . The electrical submersible pump assembly of  claim 11 , wherein the local controller is further configured to perform operations comprising:
 receiving the value of the dielectric condition of the dielectric oil in the motor head;   comparing the value of the dielectric condition of the dielectric oil in the motor head to a threshold value of the dielectric condition of the dielectric oil in the motor head; and   based on a result of the comparison, adjusting the life expectancy of the motor.   
     
     
         13 . The electrical submersible pump assembly of  claim 12 , further comprising a dielectric sensor coupled to the motor, the dielectric sensor configured to:
 sense a dielectric condition of the dielectric oil in the motor;   transmit a signal representing a value of the dielectric condition of the motor; and   the local controller is further configured to perform operations comprising:
 receiving the value of the dielectric condition of the dielectric oil in the motor; 
 comparing the value of the dielectric condition of the dielectric oil in the motor to a threshold value of the dielectric condition of the dielectric oil in the motor; and 
 based on a result of the comparison, adjusting the life expectancy of the motor. 
   
     
     
         14 . The electrical submersible pump assembly of  claim 12 , further comprising a dielectric oil accumulator configured to supply clean dielectric oil into a downhole end of the motor, wherein the local controller is further configured to perform operations comprising, based on the result of the comparison, supplying clean dielectric oil from the dielectric oil accumulator into the motor. 
     
     
         15 . The electrical submersible pump assembly of  claim 14 , wherein the local controller is further configured to supply the clean dielectric oil from the dielectric oil accumulator into the motor, through the motor, into the motor head, and out the motor head. 
     
     
         16 . The electrical submersible pump assembly of  claim 14 , wherein the local controller is configured to perform operations comprising, based on the result of the comparison, operating the dielectric oil accumulator to flow the clean dielectric oil from the local controller to the motor head for one or more of a preset time or until the result of the comparison indicates a healthy dielectric oil quality condition in the motor head. 
     
     
         17 . An electrical submersible pump motor head comprising:
 a motor head case;   a pothead coupled to the motor head case;   one or more toroidal transformers positioned within the motor head case;   a power cable positioned within the motor head case, the power cable coupled to the pothead and extending through the one or more toroidal transformers; and   a sensor module configured to perform operations comprising:
 receiving power from the one or more toroidal transformers; 
 detecting a condition of the motor; and 
 transmitting a signal representing the condition of the motor; and 
   a local controller contained within the motor head, the local controller coupled to the motor and the sensor module, the local controller configured to perform operations comprising:
 receiving electrical power from the one or more toroidal transformers; 
 receiving the signal representing the condition of the motor; 
 based on the condition of the motor, determining a mass flow rate of the motor; and 
 based on the mass flow rate of the motor, determining a life expectancy of the motor. 
   
     
     
         18 . The electrical submersible pump motor head of claim  18 , wherein the condition of the motor is the differential temperature across the outer surface of the motor, determining the mass flow rate of the motor comprises calculating the mass flow rate by 
       
         
           
             
               
                 
                   m 
                   ˙ 
                 
                 = 
                 
                   
                     Q 
                     ˙ 
                   
                   
                     
                       C 
                       p 
                     
                     ( 
                     
                       
                         T 
                         out 
                       
                       - 
                       
                         T 
                         in 
                       
                     
                     ) 
                   
                 
               
               , 
             
           
         
       
       wherein {dot over (m)} is the mass flow rate of fluids in kg/sec through the motor, {dot over (Q)} is the energy supplied to the motor in Watts, C p  is a specific heat capacity of the fluid in J/kgK in the motor, T out  is a fluid temperature at the motor uphole end in ° C., and T in  is a fluid temperature at the motor downhole end in ° C. 
     
     
         19 . A method comprising:
 generating power by one or more toroidal transformers in a motor head of an electrical submersible pump;   supplying the power to a sensor module and a local controller positioned in the motor head;   determining a differential temperature across an outer surface of the motor;   based on the differential temperature across the outer surface of the motor, determining a mass flow rate of a fluid flowing through the motor by   
       
         
           
             
               
                 
                   m 
                   ˙ 
                 
                 = 
                 
                   
                     Q 
                     ˙ 
                   
                   
                     
                       C 
                       p 
                     
                     ( 
                     
                       
                         T 
                         out 
                       
                       - 
                       
                         T 
                         in 
                       
                     
                     ) 
                   
                 
               
               , 
             
           
         
       
       wherein {dot over (m)} is the mass flow rate of the fluid in kg/sec in the motor, {dot over (Q)} is the power supplied to the motor in Watts, C p  is a specific heat capacity of the fluid in J/kgK in the motor, T out  is a fluid temperature at a motor uphole end in ° C., and T in  is a fluid temperature at a motor downhole end in ° C.; and
 based on the mass flow rate of the motor, determining a life expectancy of the motor. 
 
     
     
         20 . The method of  claim 19 , wherein, determining the life expectancy of the motor based on the mass flow rate of the motor comprises comparing the actual energy loss and the determined mass flow rate to a design energy loss and a design mass flow rate for the motor on an efficiency curve plot.